The use of Substitute Natural Gas (SNG) was proposed during the energy crisis in the 1970s. Today, SNG is becoming important as SNG production may potentially mitigate greenhouse gas emissions and enhance the diversity of energy and chemical resources. Combining gasification and catalytic methanation technologies may enable production of SNG from a variety of feedstocks such as coal, biomass and waste.
Currently, several commercial SNG plants are being built worldwide. In particular, coal-to-SNG technologies are becoming the new focus in China's coal-based chemical industry. For example, about 15 coal-to-SNG projects are being considered in China. It is estimated that China will have around 20 billion Nm3/a SNG capacity in 2015.
A simplified SNG production process is as follows: Feedstock, i.e., coal and biomass→Gasification→Gas cleaning and conditioning→Fuel upgrading.
One of the steps in commercial SNG production is methanation, which is a reaction that generates methane from a mixture of gases, for example, those derived from gasification of coal, biomass and waste. There is thus a need for catalysts robust enough for use in catalysing methanation reactions and which ensure a high methane yield. As sulfur poisoning of catalyst surfaces represents a major challenge in the field of catalysis, and of methanation catalysis more particularly, there is also a need for catalysts having good chemical and physical stabilities including resistance to sulfur poisoning. Further, there is a need for catalysts having improved coking resistance, as coke deposition on catalyst surfaces can lead to a drop in catalytic activity and selectivity.
It is an object of the invention to at least partially satisfy the above needs.